柱状节理玄武岩卸荷力学特性的数值模拟

Numerical Simulation of Mechanical Properties of Columnar Jointed Basalt Under Unloading Condition

白鹤滩水电站厂区内的柱状节理玄武岩是由原生节理与隐晶裂隙共同切割形成的节理岩体.由于两种节理的形成机理、结构形式、空间产状、力学特性的不同,使得柱状节理玄武岩在不同应力状态下,具有不同的破坏模式.利用D-CRDM分析方法对柱状节理玄武岩卸荷过程进行了计算分析,同时结合现场声波测试结果分析柱状节理玄武岩的破坏机理与模式.研究表明:卸荷过程中原生节理在张拉作用下易产生表层的剥离破坏,而隐晶裂隙在拉、压状态下均会产生开裂破坏,并诱发岩体的整体失稳.岩体的现场破坏证明了该研究结果的正确性,同时研究结果为洞室的岩体支护方式的选择提供了参考依据.

Columnar jointed basalt in Baihetan hydropower station is jointed rock mass formed by the combined cutting effect of original joint and aphanitic micro-cracks. Due to the difference of born modes, structures, attitudes and mechanical properties, the failure mode of columnar jointed basalt under various stress states is diverse. In this paper, D-CRDM method was used to simulate unloading process of columnar jointed basalt, and to analyze the failure mechanism and mode of columnar jointed basalt combining with in-situ AE test. This study indicates that in the unloading process, original joints are easy to cause surface spalling in tension state whereas aphanitic micro- cracks were inclined to induce internal cracks of surrounding rock in tension or compression and overall collapse of rock mass. The research results are justified by in-situ observations, and meanwhile, it provides a reference in the selection of supporting methods for underground cavern.